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1、专 业 英 语,Specialized English,Unit 10：,第二部分 通信技术,Introduction to Computer Netwroks,计算机网络介绍,Specialized English on Communication Engineering,NEW WORDS AND PHRASES,peripheral adj. 外围的 n. 外围设备 memory n. 存储器,内存 processor n. 处理器 central processing unit (CPU) 中央处理器 congestion n. 充满，拥挤，拥堵 topology n. 拓扑，布局 m
2、ainframe n. 主机，大型机 bus n. 总线 terminal n. 终端 bidirectional adj. 双向的 token n. 令牌 device n. 设备，装置，器械，部件 access vt. 访问，通路， 入门；accessing,Specialized English on Communication Engineering,During the 1950s, most computers were similar in one respect. They had a main memory, a central processing unit (CPU),
3、and peripherals. main memory ：主存储器 central processing unit ：中央处理器 peripheral：外围设备 in one respect ：在一个方面, 在一点上 在20世纪50年代，大多数的计算机有一点是相似的，即都有一个主存储器，一个中央处理器和一些外围设备。,TEXT,Specialized English on Communication Engineering,Since then a new generation of computing has emerged in which computation and data st
4、orage need not be centralized. computation ：计算 data storage ：数据保存 centralized ：集中的 此后出现了新一代的计算机，其计算和数据存储不必集中。,Specialized English on Communication Engineering,A user may retrieve a program from one place, run it on any of a variety of processors, and send the result to a third location. retrieve ：取回
5、，找回，获得，恢复 run ：运行 processor：处理器 用户可以从一个地方获得程序，在任何一个处理器上运行，并将结果输送到第三方。,Specialized English on Communication Engineering,A system connecting different devices such as PCs, printers, and disk drives is a network. PC： Personal Computer，个人计算机 disk drive ：磁盘驱动器 将不同设备，如个人计算机，打印机和磁盘驱动器连接起来的系统就是一种网络。,Special
6、ized English on Communication Engineering,Typically, each device in a network serves a specific purpose for one or more individuals. For example, a PC may sit on your desk providing access to information or software you need. device ：设备 individual ：个人 通常情况下，网络中的每一个设备为一个或多个用户提供一种特定的服务。例如，计算机可能会在你的案头
7、，提供你需要的信息或软件。,Specialized English on Communication Engineering,A PC may also be devoted to managing a disk drive containing shared files. We call it a file server. devoted to ：专用于 file server：文件服务器 计算机也可以专用于管理共享文件的磁盘驱动器。我们称之为文件服务器。,Specialized English on Communication Engineering,Often a network cov
8、ers a small geographic area and connects devices in a single building or group of buildings. Such a network is a local area network (LAN). geographic area ：地理区域 local area network ：局域网（LAN） 通常一个网络覆盖一个小的地理区域，并且在一个单幢建筑或建筑群中连接设备。这样的网络就是局域网。,Specialized English on Communication Engineering,A network tha
9、t covers a larger area such as a municipality, state, country, or the world is called a wide area network (WAN). municipality ：市，自治市 state ：州 wide area network ：广域网（WAN） 覆盖更大范围的网络，例如一个城市，一个州，一个国家或世界，被称为广域网。,Specialized English on Communication Engineering,Generally speaking, most networks may involv
10、e many people using many PCs, each of which can access any of many printers or servers. With all these people accessing information, their requests inevitably will conflict. access: vt. 访问；accessing inevitably :不可避免的; 无法避免的; 必然(发生)的 conflict :冲突 一般来说，大多数网络可能涉及很多人使用许多计算机，每个人都可以访问许多打印机和服务器。在这么多人存储信息的情
11、况下，不可避免的会发生冲突。,Specialized English on Communication Engineering,Consequently, the devices must be connected in a way that permits an orderly transfer of information for all concerned. concerned :有关的 因此，设备必须按照某种方式连接，该方式使各有关方面有序地传输信息。,Specialized English on Communication Engineering,A good analogy is
12、a street layout in a large city. With only one person driving it matters little where the streets are, which ones are one-way, where the traffic signals are, or how they are synchronized. analogy ：类似, 类推 one-way ：单行道的 synchronized ：同步的 with ：当(有).情况下 一个很好的比喻就是大城市的街道布局。当只有一个人驾驶时，街道在哪，哪些是单行道，交通信号在哪里，或
13、者如何同步，这些都是无关紧要的。,Specialized English on Communication Engineering,But with thousands of the cars on the streets during the morning rush hour, a bad layout will create congestion that caused major delays. rush hour ：高峰时间 layout ：设备布置，布局，规划 congestion ：（交通的） 拥挤； 但是在早晨交通高峰时间，当成千上万的汽车开上大街，一个差劲的布局会造成拥挤，从
14、而引起重大延滞。,Specialized English on Communication Engineering,The same is true of computer networks. They must be connected in a way that allows data to travel among many users with little or no delay. 计算机网络也是一样。它们必须以一种能让数据在许多用户间几乎没有延时的传播方式进行连接。,Specialized English on Communication Engineering,We call t
15、he connection strategy the network topology. The best topology depends on the types of devices and user needs. What works well for one group may perform dismally for another. strategy ：策略，方法 network topology ：网络拓扑 我们称这种连接方法为网络拓扑。最好的拓扑结构取决于设备的类型和用户的需求。对某用户组工作地很好的网络可能不适用于另外的用户组。,Specialized English on
16、 Communication Engineering,Fig. 2-11 shows a common bus topology (or simply bus topology) connecting devices such as workstations, mainframes, and file servers. They communicate through a single bus (a collection of parallel lines). workstation：工作站 mainframe：主机，大型机 图2-11表示了一种常用的（简单的）总线结构，该结构连接了如工作站、大型机和文件服务器等设备。它们通过一条总线（一组并行线）进行通信。,
